Metal/Semiconductor and Transparent Conductor/Semiconductor Heterojunctions in High Efficient Photoelectric Devices: Progress and Features

Abstract

Metal/semiconductor and transparent conductive oxide (TCO)/semiconductor heterojunctions have emerged as an effective modality in the fabrication of photoelectric devices. This review is following a recent shift toward the engineering of TCO layers and structured Si substrates, incorporating metal nanoparticles for the development of next-generation photoelectric devices. Beneficial progress which helps to increase the efficiency and reduce the cost, has been sequenced based on efficient technologies involved in making novel substrates, TCO layers, and electrodes. The electrical and optical properties of indium tin oxide (ITO) and aluminum doped zinc oxide (AZO) thin films can be enhanced by structuring the surface of TCO layers. The TCO layers embedded with Ag nanoparticles are used to enhance the plasmonic light trapping effect in order to increase the energy harvesting nature of photoelectric devices. Si nanopillar structures which are fabricated by photolithography-free technique are used to increase light-active surface region. The importance of the structure and area of front electrodes and the effect of temperature at the junction are the value added discussions in this review.

Optical and Photoconductive Response of CuO Nanostructures Grown by a Simple Hot-Water Treatment Method

“…In addition, the absorptance spectrum of the AZO/CuO/Cu device demonstrated enhanced light absorption in the NIR compared to CuO/Cu. This can originate from multiscattering effects introduced by the AZO layer and a more gradual change of the refractive index from air to the CuO NS active layer compared to that of the CuO/Cu sample. − AZO can have a refractive index within the range 1.74–2.13 in the visible region of the spectrum (about 360–760 nm). This falls in between the refractive indexes of air (∼1.00) and CuO (∼2.63), which can enhance the antireflection characteristics. , Therefore, AZO/CuO/Cu devices seem to have an antireflection property over a wide range of wavelengths.…”

“…The experimental UV/vis/NIR diffuse reflectance results of CuO nanostructures are shown in the inset of Figure . The Kubelka–Munk function [ F ( R ∞ )] is given by where R is the diffuse reflectance, α the absorption coefficient, and s is the scattering factor.…”

“…The conventional photoelectric device performance based on the conversion of light energy into photocurrent is the outcome of several complicated processes such us electron–hole generation, recombination, and trapping. ,, However, relatively low photocurrent performance of the AZO/CuO/Cu device, despite the high absorption, might be attributed to the small active contact area between the CuO/Cu junction. Furthermore, low photocurrent performance may be linked to the high recombination rate of the photogenerated electrons.…”

Doping-Dependent Optical Response of a Hybrid Transparent Conductive Oxide/Plasmonic Medium

“…This type of hybrid plasmonic-TCO systems in which the optical and electrical response can be controlled, are extremely promising for the realization of innovative plasmo-and opto-elctronics devices for ultrafast and steady-state applications. 18,25,26,28,[31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46] We based our investigations of these hybrid systems upon a very precise assessment of their dielectric characteristics (stand-alone TCO, and hybrid NP/TCO), providing solid foundations for assessing the overall optical response. We addressed the optical properties of Au NPs deposited on bare and Al-doped ZnO films by means of spectroscopic ellipsometry (SE), taking the optical response of the bare TCO films as a starting point for the discussion.…”

Enhanced Optical and Electrical Properties of ITO/Ag/AZO Transparent Conductors for Photoelectric Applications

“…One such use of the heterojunction devices is the implementation of transparent conducting oxide (TCO) layers in the Si-based devices, and it is one of the important developments in the ongoing progress of photovoltaic research [3].…”